动态为DropDownList添加Item

最新推荐文章于 2021-01-03 11:11:38 发布

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最新推荐文章于 2021-01-03 11:11:38 发布

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文章标签： xhtml ui c#

本文介绍如何使用ASP.NET MasterPage实现在子页面输入内容后动态更新主页面下拉列表的功能，通过定义接口和利用Session保存数据，实现了跨页面的数据交互。

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先看演示：

Insus.NET在MasterPage放置了一个DropDownList和一个Button控件，然后在Default.aspx放置一个TextBox。从上面的动画中可以看到，在TextBox输入文字，它会动态添加至MasterPage的DropDownList控件中。

实现过程，首先写一个接口：

IGetable

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

/// <summary>
/// Summary description for IGetable
/// </summary>
namespace Insus.NET
{
     public interface IGetable
    {
         string TextBoxValue
        {
             get;
        }
    }
}

接下来，新建MasterPage：

InsusMasterPage.master:

InsusMasterPage.master

<% @ Master Language = " C# " AutoEventWireup = " true " CodeFile = " InsusMasterPage.master.cs " Inherits = " InsusMasterPage " %>

<! DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd" >

< html xmlns ="http://www.w3.org/1999/xhtml" >
< head runat ="server" >
     < title ></ title >
</ head >
< body >
     < form id ="form1" runat ="server" >
     < div >
         < asp:DropDownList ID ="DropDownList1" runat ="server" Width ="100" >
         </ asp:DropDownList >
         < asp:Button ID ="Button1" runat ="server" Text ="Add Item" OnClick ="Button1_Click" />
         < asp:ContentPlaceHolder id ="ContentPlaceHolder1" runat ="server" >

         </ asp:ContentPlaceHolder >
     </ div >
     </ form >
</ body >
</ html >

InsusMasterPage.master.cs代码，重点部分已经有注释，难度应该不大:

InsusMasterPage.master.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using Insus.NET;

public partial class InsusMasterPage : System.Web.UI.MasterPage
{
    // Insus.NET:宣告一个泛型，将存储输入的数据
    List< string> list = new List< string>();

     protected void Page_Load( object sender, EventArgs e)
    {
         if (!IsPostBack)
        {
            Data_Binding();
        }
    }

     private void Data_Binding()
    {
         this.DropDownList1.DataSource = list;
         this.DropDownList1.DataBind();

    }

     protected void Button1_Click( object sender, EventArgs e)
    {
         // Insus.NET:把page转为接口，并取属性
         string v = ((IGetable) this.Page).TextBoxValue;

        // Insus.NET:判断Session是否为空
         if (Session[ " db "] != null)
        {
            // Insus.NET:如果不为空，直接从Session取出
            list = (List< string>)Session[ " db "];
        }
         else
        {
             // Insus.NET:如果为空，new一个实例
            list = new List< string>();
        }

        // Insus.NET:把输入值加入泛型
        list.Add(v);

         // Insus.NET:存入Session
        Session[ " db "] = list;

        Data_Binding();
    }
}

最后，是Aspx的代码：

Default.aspx:

View Code

<% @ Page Title = "" Language = " C# " MasterPageFile = " ~/InsusMasterPage.master " AutoEventWireup = " true " CodeFile = " Default.aspx.cs " Inherits = " _Default " %>

< asp:Content ID ="Content1" ContentPlaceHolderID ="ContentPlaceHolder1" Runat ="Server" >
< asp:TextBox ID ="TextBox1" runat ="server" ></ asp:TextBox >
</ asp:Content >

Default.aspx.cs:

View Code

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using Insus.NET;

public partial class _Default : System.Web.UI.Page,IGetable
{
     protected void Page_Load( object sender, EventArgs e)
    {

    }

     // Insus.NET：实现接口
     public string TextBoxValue
    {
         get {
             return this.TextBox1.Text;
        }
    }
}

好了，非常简单的例子。